De Virgiliis Andres, Meyra Ariel, Ciach Alina
Instituto de Física de Líquidos y Sistemas Bilógicos, Facultad de Ciencias Exactas-UNLP-CONICET, La Plata 1900, Argentina.
Departamento de Ciencias Básicas, Facultad de Ingeniería, Universidad Nacional de La Plata, La Plata 1900, Argentina.
Curr Issues Mol Biol. 2024 Sep 26;46(10):10829-10845. doi: 10.3390/cimb46100643.
Recent studies revealed anomalous underscreening in concentrated electrolytes, and we suggest that the underscreened electrostatic forces between membrane proteins play a significant role in the process of self-assembly. In this work, we assumed that the underscreened electrostatic forces compete with the thermodynamic Casimir forces induced by concentration fluctuations in the lipid bilayer, and developed a simplified model for a binary mixture of oppositely charged membrane proteins with different preference to liquid-ordered and liquid-disordered domains in the membrane. In the model, like macromolecules interact with short-range Casimir attraction and long-range electrostatic repulsion, and the cross-interaction is of the opposite sign. We determine energetically favored patterns in a system in equilibrium with a bulk reservoir of the macromolecules. Different patterns consisting of clusters and stripes of the two components and of vacancies are energetically favorable for different values of the chemical potentials. Effects of thermal flutuations at low temperature are studied using Monte Carlo simulations in grand canonical and canonical ensembles. For fixed numbers of the macromolecules, a single two-component cluster with a regular pattern coexists with dispersed small one-component clusters, and the number of small clusters depends on the ratio of the numbers of the molecules of the two components. Our results show that the pattern formation is controlled by the shape of the interactions, the density of the proteins, and the proportion of the components.
最近的研究揭示了浓缩电解质中存在异常的筛选不足现象，并且我们认为膜蛋白之间未充分屏蔽的静电力在自组装过程中起着重要作用。在这项工作中，我们假设未充分屏蔽的静电力与脂质双层中浓度涨落所诱导的热力学卡西米尔力相互竞争，并针对在膜中对液相有序和液相无序区域有不同偏好的带相反电荷的膜蛋白二元混合物建立了一个简化模型。在该模型中，同类大分子通过短程卡西米尔吸引力和长程静电排斥力相互作用，且交叉相互作用的符号相反。我们确定了与大分子体相储库处于平衡状态的系统中能量上有利的模式。由两种组分的簇、条纹和空位组成的不同模式对于不同的化学势值在能量上是有利的。利用巨正则系综和正则系综中的蒙特卡罗模拟研究了低温下热涨落的影响。对于固定数量的大分子，一个具有规则模式的单一两组分簇与分散的小单组分簇共存，并且小簇的数量取决于两种组分分子数量的比例。我们的结果表明，模式形成受相互作用的形式、蛋白质的密度以及组分的比例控制。
